Spondylolysis is a condition in which a crack or fracture occurs in rear portions of vertebrae of a patient's spinal column. The spinal column includes a ring of bone located at the middle and posterior portion of the spinal column that protects the spinal cord within the spinal column. The specific area that becomes cracked or fractured is known as the pars interarticularis, or pars, and is the area between a pedicle and lamina of a vertebra.
The crack or fracture, often known as a “pars fracture” or “pars defect,” is generally caused by excessive or repeated strain to the pars area, although congenital effects may also cause a pars fracture. Spondylolysis commonly occurs in the lower back at lumbar vertebra number five (L5). For example, Spondyloysis may affect athletes that repeatedly bend backwards, such as athletes in gymnastics, karate, and/or football.
Under strain, a vertebra will initially add bone cells around an injured area. However, once the strain is too great, or too violent, a stress fracture will form in the vertebra. Such a fracture will often occur within the pars, and multiple and/or persistent fractures lead to a pars defect.
In some cases, a pars defect will occur on two sides of a vertebra. When this occurs, a vertebra may translate or move towards or away from neighboring vertebrae, leading to a condition known as Spondylolisthesis.
In order to illustrate where Spondyloysis occurs, FIGS. 1A-1B depict views of a pars fracture or defect within a vertebra. FIG. 1A illustrates a side view 100 of vertebrae of a spinal column. Vertebra 110 is separated from vertebra 120 by a disk 115. Vertebra 110 is a healthy vertebra, with a pedicle 112 and lamina 114 surrounding a pars area. In contrast, vertebra 120 in an unhealthy or affected vertebra, with a pedicle 122 and lamina 124 surrounding a pars fracture or defect 125. That is, the pars fracture 125 occurs in vertebra 120 between a pedicle 122 and lamina 124 of the vertebra.
FIG. 1B depicts the pars defect from another view, namely from a top view 130 of the vertebra 120. The pars fracture 125 is located between the pedicle 122 and the lamina 124, and may cause separation of the lamina 124 from the pedicle 122. Once separated, or partially separated, the lamina 124 may translate or move relative to the pedicle 122, causing pain and/or other problems.
Conventional treatment of Spondyloysis, Spondylolisthesis, and other conditions due to fractures in the pars interarticularis of a vertebra include (1) the fusing together of vertebral segments surrounding a pars fracture or (2) the attempting to repair the pars fracture. However, there are disadvantages with conventional treatments.
Fusing vertebral segments together often leads to a loss of motion across an affected area, which may cause additional stress to surrounding vertebrae and accelerate arthritis and other conditions within the vertebrae.
Conventional repair procedures, such as using wires or screws to hold vertebral fragments together, suffer from high failure rates, because the procedures often do not maintain fractured vertebral fragments in proper position during a bone grafting or other treatments.
In some cases, plates are used during surgical repairs within the spine. For example, a first reference, U.S. Published Patent Application No. 2010/0082067, to Kondrashov, entitled “System and Method to Stabilize a Spinal Column Including a Spinolaminar Locking Plate,” discloses an anchoring plate adapted to stabilize a spinal column. The anchoring plate may have a shape that conforms to a lamina of a targeted vertebra, but is used and configured in order to stabilize a spinal column and reduce compression of spinal nerves.
As another example, a second reference, U.S. Published Patent Application No. 2005/0119657, to Goldsmith, entitled “Facet Triangle Spinal Fixation Device and Method of Use,” discloses a device adapted to bilaterally secure two vertebrae together.
In both examples, the disclosed plates are generally utilized to stabilize a spinal column and proximate verterbrae within a spinal column.
While aforementioned medical devices and treatments are generally suitable for a particular purpose, such devices are not sufficiently suitable for the purpose discussed in the present invention. Thus, it is clear that there exists a need in the art for a treatment device that overcomes these problems and progresses the state of the art, as well as one that provides the additional benefits enumerated in the present application.